Diasem is a max-variety-3 scale that is equivalent to semaphore[9] with two of the small steps made larger and the other two made smaller. This results in near-just septimal intervals and better melodic properties than the meantone scales of 26edo and 31edo, which both support it. The scale can be generated by an alternating chain of subminor thirds and supermajor seconds. The name "diasem" is a portmanteau of "diatonic" and "semaphore," and is also a pun based on the diesis, a defining step size in the scale.
Comparison with semaphore and meantone in 62edo
| Name |
Structure |
Step Sizes |
Graphical Representation
|
| Semaphore |
5L4s |
10\62, 3\62 |
├─────────┼──┼─────────┼──┼─────────┼──┼─────────┼──┼─────────┤
|
| Diasem |
5L2m2s |
10\62, 4\62, 2\62 |
├─────────┼───┼─────────┼─┼─────────┼───┼─────────┼─┼─────────┤
|
| Meantone |
5L2s |
10\62, 6\62 |
├─────────┼─────┼─────────╫─────────┼─────┼─────────╫─────────┤
|
Common Diasem Tunings
| Tuning |
L:m:s |
Good Just Approximations |
Degrees |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9
|
| 26edo |
4:2:1 |
Neogothic thirds |
0.000 |
184.615 |
276.923 |
461.538 |
507.692 |
692.308 |
784.615 |
969.231 |
1015.385 |
1200.000
|
| 31edo |
5:2:1 |
Pental thirds and 7/5 |
0.000 |
193.548 |
270.968 |
464.516 |
503.226 |
696.774 |
774.194 |
967.742 |
1006.452 |
1200.000
|
| 36edo |
6:2:1 |
Septimal thirds and 3/2 |
0.000 |
200.000 |
266.667 |
466.667 |
500.000 |
700.000 |
766.667 |
966.667 |
1000.000 |
1200.000
|
| JI |
7.479:2.309:1 |
Just 7/6, 8/7, and 3/2 |
0.000 |
203.910 |
266.871 |
470.781 |
498.045 |
701.955 |
764.916 |
968.826 |
996.090 |
1200.000
|